Apparatus for molding articles with multiple basis weight or thickness

ABSTRACT

Apparatus and method for molding an article of pulp or foam material with predetermined variation in weight or thickness distribution of fiber per unit in the article wherein the apparatus comprises a movable forming assembly carrying at least one forming platen unit thereon. The platen unit is pivotally mounted on a hollow shaft and includes at least one compartmented die made up of a plurality of die sections separated from each other. The die sections communicate with a source of vacuum through the hollow shaft which is controlled by a distributor and valve arrangement whereby the period of application and duration of vacuum in at least one of the die sections is less than that of other die sections to thereby effect a variation in weight distribution of fiber per unit area of the article.

United States Patent n91 Witt et a1,

1 1 APPARATUS FOR MOLDING ARTICLES WITH MULTIPLE-BASIS WEIGHT OR THICKNESS Inventors: Edgar C. Witt, Wilbruham; Donald T. Daniele, Longmeadow, both of Mass.

[73] Assignee: Diamond International Corporatlon,

New York, N.Y.

Filed: May 23, 1974 Appl. No.: 472,871

[5 6] Relerences Cited UNITED STATES PATENTS 1.527.202 2/1925 Louisot 162/228 2.961.368 11/1960 Lyons 162/390 X 3.185.615 5/1965 Reifers 162/228 l l Nov, 25, 1975 11/1966 Wells l62/390 X 11/1974 Hornbostel etal. 162/228 X [57] ABSTRACT Apparatus and method for molding an article of pulp or foam material with predetermined variation in weight or thickness distribution of fiber per unit in the article wherein the apparatus comprises a movable forming assembly carrying at least one forming platen unit thereon. The platen unit is pivotally mounlcd on a hollow shaft and includes at least one compartmented die made up of a plurality of die sections separated t'rom each other. The die sections communicate with a source of vacuum through the hollow shaft which is controlled by a distributor and valve arrangement whereby the period of application and duration of vacuum in at least one of the die sections is less than that ol' other die sections to thereby effect a variation in weight distribution of fiber per unit area of the article.

12 Claims, 11 Drawing Figures U.S. Patent Nov. 25, 1975 Sheet 1 Of8 3,922,191

U.S. Patent Nov. 25, 1975 Sheet2of8 3,922,191

TILJ L US. Patent Nov. 25, 1975 Sheet3of8 3,922,191

ami U.S. Patent Nov. 25, 1975 Sheet 4 of 8 3,922,191

U.S. Patent Nov. 25, 1975 Sheet60f8 3,922,191

m/oTm U.S. Patent Nov. 25, 1975 Sheet7of8 3,922,191

US. Patent Nov. 25, 1975 Sheet 8 of8 3,922,191

APPARATUS FOR MOLDING ARTICLES WITH MULTIPLE BASIS WEIGHT OR THICKNESS BACKGROUND OF THE INVENTION l. Field of the invention The field of the invention is believed to be best exemplified by art in Class l62/228 and Class 425/27].

2. Description of the Prior Art This invention was developed in light of the knowledge that in pulp or like articles. such as egg cartons. certain areas of the finished articles are inherently stronger than other areas and that as a consequence the weaker areas could be strengthened by being molded at a higher basis weight or thickness of the pulp or like material.

The desideratum of multiple basis weight or thickness molded in articles have been recognized in the industry. Exemplifying prior art endeavors to carry forth theproduction of molded articles of this type are the Reifers U.S. Pat. Nos. 3.l85,6i and 3.325.349. The Reifcrs U.S. Pat. No. 3.185.615 discloses the concept of molding articles in which weaker areas are made thicker than the stronger areas by using a molding screen in which relatively large areas are blocked out in a plurality of discrete small areas in a repeated geometric pattern. According to this patent. the screen may be blocked out in a number of ways such, for example, as embedding polyethylene into the screen, spraying plas tic or paint-like material onto the screen through a stencil, or electroplating the screen in controlled areas.

in the Reifers U.S'. Pat. No. 3.325.349,-it is shown that molded articlesmay Ive-made withthe weaker areas thicker than the stronger areas by modifying the conventional molding dies by incorporating a perforated material having hole patterns and sizes which provide sufficient restriction to retard drainage and thereby to retard pulp deposit on the die during the dip interval.

- SUMMARY OF THE INVENTION foam or equivalent material in which certain areas of the finished articles are of higher basis weight or thickness than that of other areas thereof.

Accordingly. it is an object of the present invention to provide an apparatus for producing a molded article 2 two or more vacuum forming times for each forming mold.

It is further an object of this invention to provide means for effecting variation in weight or thickness distribution of fiber per unit area of a molded article.

it is still another object of this invention to minimize unnecessary stiffness of pocket section in articles as molded egg cartons. for example.

It is yet another object of this invention to effect an over-all reduction of the material required in producing molded articles whereby economy of material is achieved. 4 Another object of this invention is to provide a method of molding articles which have a reduced nesting interval which may be stacked in a reduced volume and will effect savings in transportion expenses.

Still another object of this invention is to provide means for selectively forming thick or thin areas with the same mold.

Yet a further object of this invention is to provide an apparatus and method for molding articles requiring less heat in rough drying due to the use of less material in which areas of normally high strength is of less basis weight or thickness than thatin other areas of the artiltis another object of the present invention to provide an apparatus-forproducing a molded articleiin which the areas of normally lower strength are, of higher basis.weight or thickness than the areas of greaterstrength.

it is a further object of this invention to provide an apparatus for producing a molded article in which areas normally subjected to greater stress and/or loads are of higher basis weight or thickness than areas which normally sustain lesser stressesor-loads.

it is another object of this invention to provide means for controlling the application and duration of vacuum in the forming cycle of a molding machine that allows in complex areas of the die.

Still a further object of this invention is to provide an apparatus and method for molding articles where improved hot press operation is obtained for a given tonnage of force due to the reduction in mass in the article to be compressed.

Still another object of this invention is to provide an apparatus and method for molding articles in which improved nesting thereof is obtained at the customer's level.

With the above objects in mind, applicants have developed a new and improved apparatus and method for producing molded articles of pulp. foam or equivalent material. such as egg cartons in'which such articles are of multiple basis weight or thickness in different areas thereof. A specific example of egg cartons which may be produced in accordance with the apparatus and method of the present invention is disclosed in pending U.S. application Ser. No. 465.434, filed Apr. 29. 1974 and assigned to the assignee of the instant application. Whereas the pending application mentioned above dis closes a carton including a cellulartray or pocket portion having a lower basis weight or thickness compared with cover andlock flap portions. which have a higher basis weight or thickness. the present application rclates to an apparatus and the method for producing such a carton. Moreover, the apparatus and method according to the present invention are adapted to produce acarton with hinge joints of relatively high basis weight or thickness.

It is to be clearly understood that the concept of the present invention may be applied in molding any article of multiple basis weight or thickness regardless of the nature or purpose of the variation in basis weight or thickness. in other words. whether the variation in basis weight or thickness is for purposes of saving material, increasing strength of selective areas, or for whatever reason. the desired variation may be carried out as disclosed herein. Still the apparatus and method. as disclosed herein. will be readily understood when consid ered in connection with the carton disclosed in pending application Ser. No. 465,434. mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS Brieflyreferring to the accompanying drawings, it may be readily seen that the present invention is embodied in the following-figures wherein:

FIGS. IA and: 1B jointly, represent an elevational view, partly in'section of the molding apparatus according to the present invention with some duplicated portions thereof normally extending between section line lB-IB of FIG. IA and section line lA-IA ofFIG. 18 being omitted to conserve space;

FIG. 2 is a view taken along the section line 2-2 in FIG. IA;

FIG. 3 is a view taken along the section line 3-3 in FIG. IA;

FIG. 4 is a view taken along the section line 44 in FIG. I3; I K

FIG. 5 is a plan view of a valving arrangement for a platen unit of the molding apparatus according to the present invention;

I FIG. 6 is aview taken along the section line 6-6 in FIG. 1A:

FIG. 7 is a view taken along the section line 7-7 of FIG. 5;

FIG. 8 represents the attitude and trajectory of a platen unit and associated parts as they pass through a vacuum forming cycle;

FIG. 9 is a view taken along the section line 9-9 in FIG. 8 with portions thereof broken away; and

FIG. 10 is an end view in elevation of the parts illustrated in FIG. 9

DETAILED DESCRIPTION OF THE INVENTION Referring nowto the drawings with greater particularity, it is seen in FIGS. 1A, 1B and 3 that the apparatus for forming multiple basis weight or thickness molded articlesaccording to thepresent invention includes a forming cylinder assembly 10, a rotatable cylinder l2 keyed orotherwise secured to a shaft 14 journalled in bearings 16, which in turnare supported'in fixed support beams 18. Shaft 14 is provided with a vided on the platen 36, and a cam follower,48 is constrained by a fixed cam 50 within a cam groove 52. As seen in FIG. 18 cam 50 is fixed to a support beam 18. The rocker arm 44, rocker shaft 46, cam follower 48, cam 50 and groove 52 arefarranged to control the attitude of each platen 36 to the extent that it enters a stock tank T in a position parallel to the horizontal plane or nearly so, moves through the tank, and leaves the tank maintained in the horizontal attitude or nearly so depending upon the stock level L as seen in FIG. 8. Additionally, the rocker arm 44, rocker shaft 46, cam follower 48, cam 50 and groove 52 are arranged to control the attitude of each platen so that the molding dies 42are directed radially outwardly was to facilitate transfer of the molded article to a drying die, for example, which is conventional.

Each platen 36, as best seen in FIGS. 5-7, is provided with a valve arrangement including a distributor plate 54 with sets of openings 56, $8 and 60 therein. The distributor plates 54 are secured to platens 36 between the platens 36 and molding dies 42 so that openings 56, 58 and 60 provide communication between the molding dies 42 and passages 28. As seen in FIGS. 5 and 7, the distributor plate 54 is formed with three sets of openings 56, 58 and 60 with each set being adapted to provide communication for each of three molding dies 42. Opening 56 of each set of openings is provided with a slide valve 62 adapted to be moved between open and closepositions by an operating rod 64. Valve 62 is supported for sliding movement on an apertured support plate 66 through which bifurcated flange portion 68 of valve 62 extends over operating rod 64 in straddle relationship and sandwiched within slot-70 of collar 72 of the operating rod 64. From the foregoing construction, it is seen that when valve 62 is in the extreme left position to expose the opening 56 suction from the stock tank is provided in the molding die 42 to form the moided article by communication with a vacuum driven sprocket or gear 20 at one end thereof which may be driven by chain or gear means not illustrated. Cylinder l2'is provided with a plurality of axially extending chambers 22 each having an axial opening 24 at one end, an intermediate partition 26 forming a blind closure at theother end of each cylinder 22, and radially'extending passages 28. Cylinder I2 is also'provided with a plurality of axially spaced, circumferentially extending mounting flanges 30 on which are secured bearing units 32 for forming platen units 34. The cylinder assembly 10, as disclosed, comprises twoaxially spaced sets'A and B of eight platen units 34 each of which is mounted on cylinder 12 on opposite sides of partition 26. Each platen unit 34.is carried'360' in a continuous repeating cycle on cylinder".-

Each platen unit 34- includes a pivoting platen 36 mounted on a hollow pivot shaft 38 pivotally supported in bearings 40 secured oncylinder l2ii-lollow shaft'38 has open ends for communication by way ofpassage- -28, chamber 22 witha vacuum source oran air source, depending upon the portion of the forming cycle 'ofthe apparatus, and the molding die 42 attached to platen 36.

As mentioned above each platen unit 34 includes a pivoting platen 36. Pivoting of the platen 36 and consequently theattitude of the platen 36 is controlled by a rocker arm 44, extending from a rocker shaft 46 prosource through the platen 36 and cylinder 12. Opening 56 may be closed when valve 62 is moved to the extreme right position by operating rod 64, with the latter being urged to the right, for example-by cam means, at which time suction through opening 56 is precluded while suction continues through openings 58 and 60,

which remain open. To urge operating rod 64 to the left or to the right cams 74 and 80 are-secured on the stock tank. as seen in FIGS. 8-10., For purposes of adjusting the length of molding time or period through opening 56 anadjustable cam74 isprovided to act against one end of operatingrod 64 to urge valve 62 to the left or open position. Adjustment of the position of cam 74 to alter the length of time opening 56 is open is accomplished by rotating crank 76to advance or withdraw screw 78 on which adjustable cam 74 is supported.

Fixed cam' 80 is provided atthe opposite side of the stock tank from'adjustable cam 14 to urge operating rod 64and'vaive 62 toclose opening36 so that no suc- -.tion from the stock tank takes place inthe associated portion of the forming die 42. In this way. localized for- ,rnationmay be controlled as to basis weight or-thickness of a-molded article, while other portions of the diemay be subjected to further suction molding through openings 58 and 60, for example. lnFlG. 8 Pl represents the trajectory of the operating rod 64 as each molding die 42 undergoes a forming cycle in the stock tank T. Looking at FIGS. 8 and 9 it will be seen that the fonning cylinder 12 rotates in the direction of the arcuate arrow and considering FIG. 9 movement of the platenl36 is from right to left so that operating rod 64 and valve 62 are first closed by cam 80 and then opened 'by cam 74, a

Where it isdesired'to operate the cylinder 12 in reverse for maintenance reasons, for example, a cam 82 above, is provided with a rocker arm 44 extending from a rocker shaft 46 and having cam follower 48 constrained by a fixed cam 50 in groove 52 so that each is provided as asafety feature to insure that operating t rod 64 is always in the Correct relative position.

Looking now at FIGS. 1A, 1B and 3 along with FIGS. 2 and 4, it' is noted that a substantial mirror image arrangement of setsA and B of platen units 34 are assemblcdon cylinder 12 on.-opposite sides of partition 26 which forms a blind closure. As the platen units 34 illustrated in FlGSI. lA and 1B are passing throughtheir forming cycle vacuum is supplied as indicated in the arcuate arrows to' provide suction moving up from molding die 42, hollow shaft. passages 28 through chambers 22 and out axial opening 24. it is noted at this point that in conjunctionwithfihe forming cylinder 10, port valve control 'units'84 areprovided at opposite ends thereof and whichare fixedly supported on support beams 18. Eachportvalve control unit 84 is formed with arcuate ports 92and 96 of which port 92 is for cyclical communication with two separate vacuum conduits 86 and 88 and port 96 is for cyclical communication with a pressurized air through a conduit 90. Port 92 includes an extension 94 above conduit 88. The vacuum supplied v the various sections of molding die 42 to suck pulp or like material from stock tank T.

Formation of thearticle on the. working surface of molding die42 is characterized by the structure of the die and further by the controls imposed upon the effective vacuum applied to the die sections by valve 62, operating rod 64, earns 74 and 80. Notwithstanding the fact that vacuum is connected between port 92 and up to hollow pivot shaft 38 when platen 36 enters stock tank T, operating rod 64 is moved into contact at one end thereof with fixed cam 80 which thereupon urges through conduits 86 and/or 88 which-communicate with chamber 22 through port 92when axial opening 24 moves into registration therewith whereby suction is supplied .via-chamber'f22, passage 28 and through-distributor plate 54 tomolding dies ,42 ascontrolled by valves 62., After the' molding dies;'42 have passed I through their forming 'cycles and are outofthe'sto'ck tank T vacuum continues to besupplied from conduits 86 and/or 88 which "communicate with chamber 22 through extension'94 of arcuate port 92 as axial open ing 24 moves'in registration therewith. The vacuum supplied through conduits 86 and/or 88 operates to extract water from the article as a preliminary drying step when molding die 42 is out-of stock tank T. After the axial opening 24 moves out of rcgistrationwith respect to extension 94 of arcuate port 92, it moves'into registration with a blanked-off portion 95 and then irito re gistration with arcuate port 96 through which pressur izcd 'air may besup'pliedfrom a source not shown via conduit 90, port 96, opening 24, chamber 22,'passage 28, through distributor plate 54 and into the molding dies 42 to transferthe article to a drying die, for example; when axial opening 24 moves out of registration with extension 94'jof port 92,'chamber 22 is subjected to residual.vacuum,iwhich is ventedby check valve 98 as atmospheric pressure momentarily opensit;

g 'statvueaot oreaa'rioiv' A lt should. now be]elear' that the apparatus according to the presentinvention may beoperat'ed to carry out a method of continuously forrnmolded articles,in particular cartons" of multiple basis weight or'thickness when stock tanks-Tare supplied with slurry at level L, vacuum sourees'connccted to conduits 8 6 and 88 are turned on, air pressure connected 'torconduit 90 is turned onjand sprocket or gear 20 is driven by power source operably connected thereto. Looking at FIGSQ3 and 8,'it may be seen that as forming cylinder assembly 10 is rotated in theclockwise direction',as indicated by thearrow in'FlG. 8, each platen unit 34 is sequentially moved so that platen 36 enters moves through and leaves stock tankT. Each platen unit 34, as described slide valve 62 to a position closingopening 5.6 of distributor plate 54, which opening 56 leads to a section of molding die section 42 for molding the pocket section, while at the same time vacuum is transmitted through openings 58 and 60 to other sections of die 42 for flap and cover sections, respectively, As platen 36 progresses across stock tank T operating rod 64 is moved into contact at its opposite end with-adjustable cam 74 which thereupon urges slide valve 62 to a position to expose vacuum through opening 56 of distributor plate 54 leadingto one section of die' '42 for molding the pocket section. Vacuum, of course, continues to be supplied to other sections of molding die 42 for the remaining time platen 36 travels across stock tank T. As the time at which valve 62 is to be open may be varied by adjusting'the position of cam 74, it is clear that suction formation time in the die section effected may be varied so as to obtain a predetermined basis weight or thickness pulp accretion and taken together with the entire die assembly used, an article may be formed with multiple basis weight or thickness.

Continuing from the pulp forming or suction segment of theoperation of forming cylinder 12, each platen 36 is moved out from stock' tank' T, at which time axial opening 24 continues in registration with port 92 and along extension'94 thereof where vacuum continues to be supplied from conduits 86and/or 88 to effect extraction and drainage of moisture from the pulp formed on molding die 42. Thereafter, axial opening 24 moves out of registration withextension-94 and into registration with blanked-off portion 95, at which time residual vacuumis qvente'd to atmosphere by valve 98. Then opening 24 moves into registration with port 96 so that pressurizedfair is supplied from conduit to effect transfer of the formed carton to a drying die. The pressurized air is supplied atabout22li from the upper vertical position of platen 34. it is noted here that valve 62 remains in the open position from the tinie it is opened by operating rod 64 coming'into contact with cam 74 so that both vacuum from conduit 88 and pressurized, air from conduit 90 may be transmitted to molding die 42 through opening 56 ofdistributor plate 54 as well as through openings 58 and 60. in continuing around past port 96, platen 36 moves with valve 62 in the open position until operating rod 64 strikes cam 80 which closes valve 62 once again to initiate a controlled vacuum operation for forminganother molded article of muitiple'basisweight or thickness.

From the foregoing apparatus and method of operation thereof, it is seen that multiple formation time may be achieved on a single mold so that selectively "thin" or thick areas may be formed in a molded article. It is noted that while the'apparatus as illustrated and described relate to producing articles with two different basis weight or the thickness. it is within the contemplation of the present invention to provide an apparatus and method for molding an article with two; three, four or more different bases of weight or thickness.

it is further within the contemplation of this invention to provide an apparatus and method whereby two 8 disconnect means for supplying air pressure to said molding die by way of said passage means, said hollow shaft, and said distributor means. said means for supor three or four or more different articles or different shapes and/or of different bases weight and/or thickness with different dies arranged, for example, in adjacent rows around the cylinder.

Although the invention has been described herein with particularity in connection with one illustrated form of the molding apparatus and method of use. it is to be clearly understood that the present invention has been made only by way of example and that numerous changesin details of construction may be resorted to withoutdeparting from the spirit and scope of the invention as hereafter claimed.

What is claimed is: I v

1. Apparatus for producing molded articles from pulp or foam stock material and. of multiple basis weight or thickness, said apparatus-comprising a movable forming assembly carrying at'least one forming platen unit thereon, said platen unit having at-least one compartmented moldin g'die made-up ofa plurality of die sections attached thereto, said forming assembly being movable to carry said'molding dieinto a stock tank, passage means in said forming assembly communicating with and connecting said molding die to means for supplying vacuum, distributor means disposed be? tween said molding die and said passage.rneans,1said' distributor means including at least twoopeningswhich lead to separate die sections of said molding die, a port plying air pressure being effective to enable transfer of molded articles from said molding die.

4. Apparatus as defined in claim 3 wherein said forming assembly is generally in the form ofa rotating cylinder and is movable whereby said platen unit is periodically carried in and removed from a stock tank from which stock is sucked onto said molding die by vacuum applied to said molding die from said means for supplying vacuum.

5. Apparatus as defined in claim 4 wherein said movable valve member is shiftable to positions for opening and closing said one of said openings by a rod element operably connected thereto and movable with said platen unit, a fixed cam element disposed in the path of said rod element to urge said movable valve member to its closing position and an adjustable cam element disposed in the path of said rod element to urge said movable valve member to its opening position, said adjustable cam element being adjustable in position through a range to provide zero suction or formation time to full suction or formation time.

6. Apparatus as defined in claim 5 wherein said port valve control unitincludes separate ports effective to sequentially connect and disconnect said means for supplying vacuum and said means for supplying air pressure to saidhollow shaft, saiddistributor means, and said molding die, said ports being separated from each other by a blanked-off portion, said air pressure being effective to transfer molded articles from said molding die.

t 7. Apparatus as defined in claim 6. wherein said platen unit is providedwith a rocker shaft and a rocker arm extending therefrom, said rocker arm having a follower in following relationship with a fixed cam groove whereby as said forming assembly is rotated said platen unit is directed as to its attitude depending upon the portion of the forming cycle said platen unit is in.

8. Apparatus as defined in claim -7 wherein said [platen unit isdirected by said cam groove and follower to a downwardly facing direction and maintained in an valve control unitmounted adjacent one end of said i passage means and operable to connect and disconnect said means for supplying vacuum to said passage means and to said molding die, said distributor means including a movable valve member cyclicallyopening and closing one of said openings whereby a reduced vacuum operation time in one of said diesections is effected when said molding-die is carried into astock tank and a comparable" less basis weight build-up of stock is thus achieved insaid one of said die sections,

others of saidiat least two openings being open over the entire time said moldingzdie is carried in a stock tank thereby allowing greater vacuum operation time in oth-' ers of said die sectionsandeffecting a comparably greater basis weight build-up of stock in said others of said die sections. t I

2. Apparatus as defined in claim I wherein said form; ing assembly includes bearing means pivotally supporting a hollow shaft, said platen unit is secured on said hollow shaft for pivotal movement therewith, and said hollow shaft forms an extension of said passagemeans and cooperates to connect said molding dieto said means for supplying vacuum. a

3. Apparatus as definedin claim 2 wherein said port valve control unit'is further operable to connect and attitude generally parallel to the horizontal plane as it enters the stock tank. moves through its forming cycle,

and leaves the stock tank.

9. Apparatus as defined in claim 8 wherein said platen unit is directed bysaid cam groove and follower toa radially outwardly facingQdirection to facilitate basis weight pulp or foam articles, a compartmented molding die assembly comprising a plurality of die sections, each of said die sections being separated from another die section,, screen means disposed over said die sections. separate chambers connecting said die sections to means for supplying vacuum whereby pulp or foam may be sucked onto said die sections and means II. In a molding apparatus for producing multiplein one of said chambers being effective to control the means effective to control the amount of pulp or foam at a reduced basis weight in said one of said chambers is a valve member operable to close off said means for 10 4 supplying vacuum while others of said chambers remain open to said means for supplying vacuum.

12. The die assembly as defined in claim II a second one of said die sections is adapted to form the cover section of an egg carton and a third one of said die sections is adapted to form the lock flap for an egg carton with the chambers connecting said second and said third ones of said die sections to the means for supplying vacuum so as to form cover sections and lock flap sections at a greater weight basis compared to that of pocket sections formed by said die assembly.

i i i i i 

1. Apparatus for producing molded articles from pulp or foam stock material and of multiple basis weight or thickness, said apparatus comprising a movable forming assembly carrying at least one forming platen unit thereon, said platen unit having at least one compartmented molding die made up of a plurality of die sections attached thereto, said forming assembly being movable to carry said molding die into a stock tank, passage means in said forming assembly communicating with and connecting said molding die to means for supplying vacuum, distributor means disposed between said molding die and Said passage means, said distributor means including at least two openings which lead to separate die sections of said molding die, a port valve control unit mounted adjacent one end of said passage means and operable to connect and disconnect said means for supplying vacuum to said passage means and to said molding die, said distributor means including a movable valve member cyclically opening and closing one of said openings whereby a reduced vacuum operation time in one of said die sections is effected when said molding die is carried into a stock tank and a comparable less basis weight build-up of stock is thus achieved in said one of said die sections, others of said at least two openings being open over the entire time said molding die is carried in a stock tank thereby allowing greater vacuum operation time in others of said die sections and effecting a comparably greater basis weight build-up of stock in said others of said die sections.
 2. Apparatus as defined in claim 1 wherein said forming assembly includes bearing means pivotally supporting a hollow shaft, said platen unit is secured on said hollow shaft for pivotal movement therewith, and said hollow shaft forms an extension of said passage means and cooperates to connect said molding die to said means for supplying vacuum.
 3. Apparatus as defined in claim 2 wherein said port valve control unit is further operable to connect and disconnect means for supplying air pressure to said molding die by way of said passage means, said hollow shaft, and said distributor means, said means for supplying air pressure being effective to enable transfer of molded articles from said molding die.
 4. Apparatus as defined in claim 3 wherein said forming assembly is generally in the form of a rotating cylinder and is movable whereby said platen unit is periodically carried in and removed from a stock tank from which stock is sucked onto said molding die by vacuum applied to said molding die from said means for supplying vacuum.
 5. Apparatus as defined in claim 4 wherein said movable valve member is shiftable to positions for opening and closing said one of said openings by a rod element operably connected thereto and movable with said platen unit, a fixed cam element disposed in the path of said rod element to urge said movable valve member to its closing position and an adjustable cam element disposed in the path of said rod element to urge said movable valve member to its opening position, said adjustable cam element being adjustable in position through a range to provide zero suction or formation time to full suction or formation time.
 6. Apparatus as defined in claim 5 wherein said port valve control unit includes separate ports effective to sequentially connect and disconnect said means for supplying vacuum and said means for supplying air pressure to said hollow shaft, said distributor means, and said molding die, said ports being separated from each other by a blanked-off portion, said air pressure being effective to transfer molded articles from said molding die.
 7. Apparatus as defined in claim 6 wherein said platen unit is provided with a rocker shaft and a rocker arm extending therefrom, said rocker arm having a follower in following relationship with a fixed cam groove whereby as said forming assembly is rotated said platen unit is directed as to its attitude depending upon the portion of the forming cycle said platen unit is in.
 8. Apparatus as defined in claim 7 wherein said platen unit is directed by said cam groove and follower to a downwardly facing direction and maintained in an attitude generally parallel to the horizontal plane as it enters the stock tank, moves through its forming cycle, and leaves the stock tank.
 9. Apparatus as defined in claim 8 wherein said platen unit is directed by said cam groove and follower to a radially outwardly facing direction to facilitate transfer of molded articles from said molding die as it is carried to a transfer position.
 10. Apparatus as defined In claim 9 wherein said port valve control unit is provided with check valve means for venting residual vacuum trapped in said passage means which has moved from registration with one of said ports for supplying vacuum to said molding die, past said blanked-off portion, prior to registration with the other of said ports for supplying pressurized air to said molding die for transfer of molded articles therefrom. 11.IN A MOLDING APPARATUS FOR PRODUCING MULTIPLE BASIS WEIGHT PULP OR FOAM ARTICLES, A COMPARTMENTED MOLDING DIE ASSEMBLY COMPRISING A PLURALITY OF DIE SECTIONS, EACH OF SAID DIE SECTIONS BEING SEPARATED FROM ANOTHER DIE SECTION, SCREEN MEANS DISPOSED OVER SAID DIE SECTIONS, SEPARATE CHAMBERS CONNECTING SAID DIE SECTIONS TO MEANS FOR SUPPLYING VACUUM WHEREBY PULP OR FOAM MAY BE SUCKED ONTO SAID DIE SECTIONS AND MEANS IN ONE OF SAID CHAMBERS BEING EFFECTIVE TO CONTROL THE AMOUNT OF PULP OR FOAM SUCKED ONTO ONE OF SAID DIE SECTIONS SO AS TO BE AT A REDUCED BASIS WEIGHT, A FIRST ONE SAID DIE SECTIONS BEING ADAPTED TO FORM THE POCKET SECTION OF AN EGG CARTON WHICH INCLUDES MANY SURFACES INTERSECTING AT VARIOUS ANGLES AND BEING CONNECTED TO SAID MEANS FOR SUPPLYING VACUUM TO SAID ONE OF SAID CHAMBERS HAVING SAID MEANS THEREIN TO CONTROL THE AMOUNT OF SLURRY AT A REDUCED BASIS WEIGHT, AND SAID MEANS EFFECTIVE TO CONTROL THE AMOUNT OF PLUP OR FOAM AT A REDUCED BASIS WEIGHT IN SAID ONE OF SAID CHAMBERS
 12. The die assembly as defined in claim 11 a second one of said die sections is adapted to form the cover section of an egg carton and a third one of said die sections is adapted to form the lock flap for an egg carton with the chambers connecting said second and said third ones of said die sections to the means for supplying vacuum so as to form cover sections and lock flap sections at a greater weight basis compared to that of pocket sections formed by said die assembly. 